Process Software

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Albuquerque, NM

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November 23, 2012

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Papers CHI **** ** MARCH * APRIL

Doom as an Interface for Process Management

Dennis Chao

Computer Science Department

University of New Mexico

Albuquerque, NM 87131 USA

+1-505-***-****

******@**.***.***

ABSTRACT

This paper explores a novel interface to a system adminis-

tration task. Instead of creating an interface de novo for the

task, the author modi ed a popular computer game, Doom,

to perform useful work. The game was chosen for its appeal

to the target audience of system administrators. The imple-

mentation described is not a mature application, but it illus-

trates important points about user interfaces and our relation-

ship with computers. The application relies on a computer

game vernacular rather than the simulations of physical re-

ality found in typical navigable virtual environments. Using

a computer game vocabulary may broaden an application s

audience by providing an intuitive environment for children

Figure 1: The PSDoom interface.

and non-technical users. In addition, the application high-

lights the adversarial relationships that exist in a computer

and suggests a new resource allocation scheme.

a rst-person shooter game. Each process can be represented

as a monster, and interacting with the monsters would af-

Keywords

fect the corresponding processes. The implementation of this

Cyberspace, Doom, rst-person shooter, games, metaphors,

metaphor and the great interest it generated reveal interesting

operating systems, Post-Modernism, 3D user interfaces, ver-

insights about our computers and our society.

nacular, video games, visualization

IMPLEMENTATION

INTRODUCTION

Those who use computers inevitably encounter some of the The Doom process manager (PSDoom) is a modi cation of

metaphors that allow for easier assimilation of abstract con- the game Doom [8] that displays representations of the pro-

cepts. The desktop metaphor is so pervasive that most users cesses running on a machine. Rather than using standard

hardly notice it [9], but the richness of the science- ction ver- text-mode UNIX tools to view and manipulate processes, one

sion of cyberspace is largely con ned to research laboratories surveys and shoots at a room full of bloodthirsty mutants, as

and Hollywood. The application described in this paper is an shown in Figure 1. When a user starts PSDoom, currently

initial step towards bringing a richer environment to personal running processes are instantiated as process monsters in a

computers. single room in a dungeon. These monsters have their asso-

ciated process name and id printed on them. The program

There is a large gap between how we think about perform- periodically polls the operating system to add newly-created

ing actions on our computers and how we actually perform processes to the game. The user may choose to view the pro-

them. For example, people who need to manage processes cesses from a balcony above the room, as shown in Figure 2,

on a UNIX system think about the daemons spawning chil- or to enter the room to interact with them. If the user in icts

dren that may need to be killed or blown away. This vio- a wound upon a process monster, the corresponding process

lent language suggests a metaphor for process management: priority is lowered to give it fewer CPU cycles. When the

monster accumulates enough damage and is killed, the asso-

Permission to make digital or hard copies of all or part of this work for

personal or classroom use is granted without fee provided that copies ciated process is also killed.

are not made or distributed for pro t or commercial advantage and that

copies bear this notice and the full citation on the rst page. To copy

PSDoom inherits the rest of its behavior from the original

otherwise, or republish, to post on servers or to redistribute to lists,

Doom, and play is not noticeably affected. Monsters attempt

requires prior speci c permission and/or a fee.

to attack the player and each other. The hostility of the mon-

SIGCHI 01, March 31-April 4, 2001, Seattle, WA, USA.

CHI 2001

152 Volume No. 3, Issue No. 1

CHI 2001 31 MARCH 5 APRIL Papers

Figure 2: The view from the balcony in PSDoom. Figure 3: Killing a process in PSDoom.

sters and the user s limited ammunition are disincentives to Doom is that monsters are much more likely to attack each

attack them. Con ict among process monsters could help other than expected. This causes many windows to mysteri-

regulate heavily-utilized systems by making crowded rooms ously disappear as the program runs. For the same reason,

have higher mortality rates. Killing random processes on an the computer is prone to crashing because certain processes

extremely loaded system is not an uncommon operating sys- are vital to the computer s operation and should not be killed.

tem strategy. When the user is killed, he or she will be

Many users want a larger variety of monsters in PSDoom. If

healed and placed at the entrance of the dungeon with a pis-

larger or more important processes were represented as larger

tol and a modest amount of ammunition.

monsters, it would be easier to assess the machine load at

a glance. If these monsters were also more powerful, they

Doom was chosen for this project for two reasons. The rst is

would be less likely to be killed by accident and be more able

that it is a classic game, familiar to most system administra-

to defend themselves against the player. Several users made

tors. The second is that its source code was recently released

similar suggestions for altering the appearance of monsters

under the GNU General Public License (GPL) [13]. This li-

based on certain attributes. Processes that take more memory

cense not only allows the author to modify the source code,

could appear wider, while those that take more CPU time

but it guarantees that future derivatives of the author s work

can appear taller. Sleeping processes could be represented

will be available to the public.

by napping monsters.

RESULTS

To address some of these requests, I added code to make

PSDoom received a surprisingly large reaction even though

some of the more important processes Barons of Hell, the

it was not publicized [24, 26, 4, 17]. Less than a week af-

largest monsters in the game. Unfortunately, they had a ten-

ter the initial version of the code was written, the project s

dency to quickly kill all of the other processes, and the user

website was attracting tens of thousands of visitors per day.

could not interact with processes for more than a few seconds

Approximately 800 responses were e-mailed to the author or

before his or her avatar is killed. Making the monsters less

www.slashdot.org within the rst two months. Of these re-

aggressive would allow the user to navigate among processes

sponses 27% praised the project, 23% offered suggestions

more easily as well as make the computer more stable.

for improving PSDoom, 10% found the project funny, 10%

reported technical problems, 8% related PSDoom to science

DISCUSSION

ction or to the future of interfaces, 1% disliked the project,

The enormous interest that PSDoom generated naturally raises

and 0.6% were frightened by its implications.

the question of why people nd it so compelling. Perhaps

even more interesting than the application itself is the set of

Users found the interface intuitive. One can quickly assess

issues that it raises.

machine load by seeing how crowded a room is. The com-

mand line methods to slow down and kill processes are dif-

Cyberspace Environments

ferent, while PSDoom uni es them shooting a monster

In 1981, Vernor Vinge introduced the concept of cyberspace

with a small weapon slows down or wounds the corre-

to the reading public in his novella True Names [30], in which

sponding process, and repeated rings or the use of a large

characters could plug into a virtual universe where their ac-

weapon kills the process, as shown in Figure 3. The violence

tions in a fantasy world mapped to performing sophisticated

in icted upon the monsters re ects the violent terminology

actions on the network. For example, navigating a treacher-

of UNIX commands.

ous path through a swamp in cyberspace could gain the user

A signi cant problem with the current implementation of PS- entry into a high-security network in the real world.

anyone. anywhere. 153

Papers CHI 2001 31 MARCH 5 APRIL

The use of a cyberspace environment can make performing

complex tasks easy if the mapping between the actions in the

virtual world and their effects in the real world is intuitive.

Communication among users may be facilitated because in-

teracting with a group of avatars can be made as natural as

interacting with a group of people. Doom places the user

into a 3D rst-person perspective environment that rapidly

engages the senses. Its interface is particularly suitable for

the task of process management because many system ad-

ministrators are familiar with the game and it realizes the

common metaphor of killing processes.

In PSDoom, actions that affect the processes take time and

effort. This philosophy runs counter to intuition, which tells

Figure 4: General Magic s MagicCap.

us to make everything as easy to do as possible. In a com-

mand line interface, all actions take approximately the same

amount of work, making it just as easy to erase all of one s

les as it is to remove a single one. In this cyberspace envi-

ronment, the players are not omnipotent, so actions take an

amount of effort proportional to their effects. People with

different levels of authority can be given weapons of differ-

ent strengths. An experienced system administrator can be

given a large gun, while the beginner may be forced to deal

with monsters with his or her bare hands. It would take a

foolhardy player to attack a room full of monsters, just as

a newbie should not kill a bunch of important processes. A

more experienced sysadmin would have time to stop a novice

who is trying to kill the wrong process.

The Software Vernacular

Current applications often do not leverage the rich vocabu-

lary of contemporary mass media and video games. Their

Figure 5: Microsoft Bob.

user interfaces are usually austere, re ecting the limitations

of the machines of two decades ago. Our rectilinear desktops

feature a Machine Aesthetic, not a human one. There have sentation and artistic expression [6]. The idioms of cartoons

been attempts to create friendlier interfaces based on familiar form an effective vocabulary for concise visual communica-

physical settings (e.g. General Magic s MagicCap [21] (Fig- tion with the user, but cartoons lack a crucial element of user

ure 4) and Microsoft Bob [2] (Figure 5)), but they have often interfaces: interactivity. Computer games have successfully

been derided as condescending or con ning [12]. The failure integrated concise, stylized visual representations and feed-

of these more humane interfaces may be due to the denial back from the user.

of the computer world s own vocabulary that is distinct from

that of everyday life s. In many ways, computer games have The desktop metaphor derives much of its power from the

become the vernacular of the computer world because they fact that users were traditionally of ce workers who spent

are what children and many non-technical adults use. much of their days at actual desks [12, 20]. However, in re-

cent years computers have entered the home, and the current

Interfaces that adhere strictly to a metaphor based on the generation of users is gaining increased exposure to comput-

physical world are in danger of becoming simulations of ers that are not merely of ce appliances. Children are now

reality instead of useful analogies [18]. One problem with growing up on MTV and Nintendo and are therefore more lit-

simulations is that one must closely adhere to all the restric- erate in the languages of video games and mass media than

tions of the real system. For example, in Microsoft Bob it is in that of the traditional of ce milieu. Designers should con-

disturbing to see pieces of furniture hovering over the oor sider taking advantage of the vocabulary of popular culture

in apparent violation of gravity. In contrast, it is more or instead of trapping the next generation in dioramas of subur-

less natural to have an arbitrarily large number of windows ban homes and of ces.

open on a computer desktop, which is a less-literal, and thus

less-con ning, metaphor. Cartoon-like animations have been Like the Post-Modern architects, I would like to blur the

suggested as a compromise between straightforward repre- distinction between high and low culture [29, 3] and

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CHI 2001 31 MARCH 5 APRIL Papers

bring popular culture into serious computer applications.

By adding familiar cultural elements to our interfaces, we

can make them appealing to the common user and children,

the next generation of users. These elements would bring a

sense of playfulness and ease that are usually absent from our

button- and toolbar- laden windows.

Several attempts have been made to introduce game-like el-

ements to the desktop, including the recent UBUBU Uni-

verse [27]. UBUBU replaces the hyperlinks and folders on

the desktop with navigable planets in a solar system. While

the concept is super cially similar to Bob, the choice of y-

ing through space rather than walking around a house may

engage the general public instead of being perceived as pa-

Figure 6: The UNIX top application.

tronizing. Companies like UBUBU that design products for

web-surfers are using playful game-like designs to tap into

the lucrative demographic of computer game players. avatar loses possession of the items he or she was carrying

and is sent home. About half the players enjoyed this aspect

An Adversarial Operating System

of the environment while the rest were opposed to it [23]. To

PSDoom presents an unusual perspective on our interactions

stem anarchy, the players established their own churches and

with computer programs. It is unique in that it allows the

laws. In Ultima Online [28], an online fantasy environment,

processes to ght each other and the user. Thinking of our

player-killing is an integral part of gameplay for some, but

computing environments as being adversarial can be enlight-

many value the complex social interactions with their fellow

ening. Processes are competing for machine resources, such

players even more.

as memory and CPU time, and PSDoom makes this compe-

tition explicit. The user may want to kill processes to free We have seen violent multi-user games evolve into peace-

needed resources, so from the process s perspective, the user ful virtual communities. Production values play a role in the

may be its greatest threat. The processes are given the ability suspension of disbelief essential for this to happen [19], but

to shoot back and defend themselves. even text-based MUDs, which originated as hack-and-slash

games, have become chatrooms [5]. The key elements seem

Operating systems attempt to satisfy users and processes

to be the rich interactions with other players and the persis-

through fairness policies for resource allocation. An adver-

tence of identity over multiple sessions. These seminal ex-

sarial operating system would invert the responsibility for

periments in multi-user virtual worlds are showing us how to

sharing resources by forcing the users and processes to com-

moderate violence with a sense of community.

pete directly with each other. It would simply maintain a

stable arena in which processes could compete. An offensive

RELATED WORK

and defensive arms race could ensue, but the system would

Visualizing Processes

not necessarily degrade to an hostile, anarchic environment.

The standard UNIX application to view processes is top (Fig-

Under the right conditions, processes will cooperate rather

ure 6). It is a dynamic version of ps, a command that simply

than compete [1]. They would nd it in their best interests to

lists the running processes. As implied by its name, top dis-

only attack when necessary because unduly belligerent pro-

plays the top CPU-users, refreshing at regular intervals. Its

cesses would become injured in frequent con icts and die.

interface is primitive. The user may not interact directly with

the process list an instruction and process number must be

Violence in Computer Games

entered, much like on the command line. Another limitation

It is unfortunate, especially in the light of recent schoolyard

is that the number of processes displayed is limited by the

tragedies, that rst-person shooters are so popular. Even

number of lines on the display (typically around twenty to

though studies on the effects of violent media on youth are

thirty). There is now a plethora of alternatives to top that

not conclusive [11], interface designers must proceed with

allow more interaction with the list, such as clicking on the

caution when adding potentially aggressive aspects to inter-

entries. These contribute obvious graphical additions to a

faces. One must take into consideration the age of the ex-

process display and add little conceptually.

pected user base and the possible use of non-aggressive al-

ternatives.

LavaPS [16] is a more abstract way to view processes. It

Lucas lm s Habitat [14], an early multi-user virtual envi- displays processes as colored blobs in a window, using the

ronment, faced these ethical dilemmas with the introduction size, color, and location of shapes in the window to repre-

of weapons. These weapons could kill avatars, though sent certain metrics of the processes, as shown in Figure 7.

death in Habitat is no more serious than death in Doom the More explicit information can be shown on demand. Like

anyone. anywhere. 155

Papers CHI 2001 31 MARCH 5 APRIL

affects ease-of-use, may be desirable because it can make the

task more enjoyable [22].

The use of game-like interfaces need not harm the perfor-

mance of applications. In fact, it can reduce the learning

curve. We would not need to sacri ce power games have

amazingly complex maneuvers that skilled operators can use

in addition to their simple repertoires for novices.

FUTURE WORK

It would not be dif cult to remedy the major source of in-

stability of PSDoom, the belligerence of the monsters. The

monsters currently have no sense of self-preservation. They

will continue to attack until they or their targets are elimi-

nated. One could simply make the monsters only attack when

Figure 7: Heidemann s LavaPS process visualization ap-

plication. provoked and more likely to run away rather than ght to the

end.

PSDoom, LavaPS represents processes as physical entities It would be natural to extend the program to networked envi-

with no quantitative information. However, the application ronments. In fact, many internet search engines have already

is inspired by calm technology [31] and is therefore in- classi ed PSDoom as a network tool in anticipation of this

tentionally passive. Its main purpose is to display the state feature. A networked version would allow multiple users to

of processes, and manipulating the actual processes can be communicate verbally as well as work cooperatively [10].

done through a menu. Turning this single-player game environment into an online

world could reduce the level of violence by increasing the

Game-like Interfaces sense of community.

The CHI 97 Workshop on Game Design and HCI suggests

By selecting only certain types of processes to appear in the

that computer game design has much to offer to the HCI com-

dungeon, one can change the nature of PSDoom. For in-

munity, but little has been done so far [7]. A popular area for

stance a lter that only allows suspicious or possibly cor-

game-like interfaces is software for children. Such products

rupted processes [25] to appear would turn PSDoom into a

range from educational games to tools that encourage cre-

security program. Alternatively, one can choose to display

ativity, such as authoring tools. It is dif cult to make direct

only large users of memory or bandwidth in order to allevi-

comparisons between software for children and software for

ate pressure on these resources.

adults because the expectations we have for the intended au-

diences are so different. Designers readily use entertaining

CONCLUSION

interfaces to keep children engaged [15]. Even in educational

PSDoom presents a novel approach to process visualization

software, in which the ultimate goal is to teach the user, the

and manipulation that illuminates many aspects of our rela-

proximate goal is to keep the child engaged, or else the ul-

tionship with computers. The popularity of this early pro-

timate goal will never be reached. In application software

totype demonstrates that interfaces inspired by video games

for adults, the burden of staying focused is on the user. The

and science ction are eagerly awaited by a large audience.

measurement for success is not how enjoyable the software

Computer games are a rich and often overlooked source of

is but rather how effectively it accomplishes a task.

technology and metaphors for user interfaces that will only

increase in importance as children, the next generation of

The contrast between software for these two audiences high-

users, grow up with computers. Our computer environments

lights the difference between enjoyment and ergonomics. A

are rapidly becoming an anachronism as people who have

piece of children s software must look good and be fun, while

never handled actual le folders are forced to use their virtual

software for adults must work. These are not necessarily con-

counterparts. The process of changing interface metaphors

icting goals, as an interface that is dif cult to use will also

will expose previously-obscured facets of the underlying ap-

adversely affect the user s enjoyment. However, for seri-

plications, such as the genuinely adversarial interactions in

ous software, concessions to make a program more enjoy-

our operating systems. Interested programmers can explore

able might not be implemented because they can not be jus-

and modify the code for PSDoom, which is available at

ti ed on ergonomic grounds.

http://www.cs.unm.edu/ dlchao/ ake/doom.

For an application that helps the user monitor the state of a

system, like PSDoom, the case for making user interfaces ACKNOWLEDGMENTS

more engaging is compelling. Keeping the user engaged is I would like to thank the Adaptive Computation Group at

as important as making the tasks easy to perform. In such UNM for providing a supportive environment in which one

cases, the use of randomness in a program, which adversely can claim one is doing research while playing Doom for

CHI 2001

154 Volume No. 3, Issue No. 1

156

CHI 2001 31 MARCH 5 APRIL Papers

two days. The offhand remarks of Anil Somayaji provided 14. Habitat. Lucas lm Ltd, San Rafael CA, 1986.

the initial inspiration for the project. David Ackley, Ben

15. Hakansson, J. Lessons Learned From Kids: One Devel-

Bederson, Patrik D haeseleer, Stephanie Forrest, and Jason

oper s Point of View. The Art of Human-Computer Inter-

Stewart provided helpful comments that improved this paper.

face Design, edited by Brenda Laurel. Addison-Wesley

This work was partially supported by the National Science

Publishing Company, Inc., New York, 1990.

Foundation (grants NSF-9553623, CDA-9503064, and IRI-

9711199) and the Of ce of Naval Research (grant N00014- 16. Heidemann, J. LavaPS. 1998. Available at

99-1-0417). http://www.isi.edu/ johnh/SOFTWARE/LAVAPS/.

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